CHICAGO – U.S. Rep. Jesse Jackson is taking a medical leave of absence and is being treated for exhaustion.

The congressman's office made the announcement in a three-sentence statement Monday afternoon. The office did not say how long Jackson would be away, but said he started his leave on June 10. It said his offices remain open for constituent services.

Jackson first won office in 1995 and represents Illinois' 2nd District, which includes Chicago's South Side and the city's southern suburbs. He is under investigation by the House Ethics Committee.

Jackson faces allegations that he was involved in discussions about raising money for then-Illinois Gov. Rod Blagojevich's campaign in exchange for an appointment to President Barack Obama's old Senate seat.